Fluid containers having an inner acid reacting layer

ABSTRACT

A rupturable, single use fluid container adapted to retain a photographic composition is composed of a plurality of layers including a layer of metal foil, particularly aluminum foil, and a layer containing an acid-reacting reagent.

United States Patent v Campbell [45] Mar. 14, 1972 [54] FLUID CONTAINERS HAVING AN 2,898,208 8/1959 Land et al ..96/76 INNER ACID REACTING LAYER 2,653,732 9/1953 Land [72] Inventor: John E. Campbell, Needham, Mass. primary Emminer Noman Torchin [73] Assignee: Polaroid Corporation, Cambridge, Mass. Emminer 1ohn Goodrow AttorneyBrown and Mikulka, Robert M. Ford and Philip G. [22] Filed: Apr. 15, 1970 i l 21 A 1. No.1 28 786 l 1 pp [57 ABSTRACT 52 u.s.c| ..96/76, 222/107 A rumurablo, single use fluid container adapted to retain a 51 Int. Cl ..G03c l/48 Photographic composition is composed of a plurality of layers 58] Field of Search ..206/56 AA; 222 107; 96/76 including a layer of metal foil, particularly aluminum foil, a

a layer containing an acid-reacting reagent. [56] References Cited UNITED STATES PATENTS Campbell 9 6/76 13 Claims, 4 Drawing Figures PATENTEDMAR 14 1972 3.649282 INVENTOR. JOHN E. CAMPBELL blown mm FLUID CONTAINERS HAVING AN INNER ACID REACTING LAYER BACKGROUND OF THE INVENTION In the photographic processes identified hereinafter, frequently it is required that a small quantity of liquid material be applied in a relatively thin layer over a fairly large surface area. Specifically, for example, a photosensitive film may be processed by the application to a surface of a layer of a liquid containing photographic processing reagents, for example, a silver halide developing composition of the type disclosed in US. Pat. No. 2,543,181. In general, photographic fluid processing compositions possess a relatively limited shelf life due to, in part, the degradation effects of environmental conditions upon the active components of the processing compositions. For example, the presence of environmental oxygen in contact with a liquid photographic processing composition generally provides for the oxidative degradation of various active components of the composition such as, for example, the photographic silver halide developing agents retained within such formulations, which may be further catalyzed by contact between the liquid and the container retaining same, where such retaining means are not inert with respect to the liquid. In an effort to provide fluid containers particularly adapted to retain a relatively small quantity of liquid material for the above-identified purpose, several patents have been issued directly relating to the construction of such fluid containers. US. Pat. Nos. 2,543,181; 2,634,886; 2,653,732; 2,674,532; 2,702,146; 2,723,051; 2,750,075; 2,903,829; 2,992,102; 3,056,491; 3,056,492; 3,221,942; 3,173,580 and 3,438,550 disclose fluid containers particularly adapted to retain photographic processing compositions which are formed of a plurality of layers including, respectively, an outer layer, for example, kraft paper; a layer of metallic foil, for example, lead foil or aluminum foil; and an inner lining, or layer, of a thermoplastic resin, for example, a polyvinyl acetal such as polyvinyl butyral, polyvinyl chloride, and the like. The presence of minute defects in the polymeric inner liner such as, for example, pinholes and the like, arising during fabrication of the container, further adversely affect the stability of the retained fluid compositions, by providing contact of the liquid with the potentially active metallic foil stratum of the container. This problem is particularly critical with the employment of aluminum as the metallic foil since the photographic processing composition disposed in such containers includes an alkaline material. Whereas sodium hydroxide, for example, contacting a layer of lead would result in reaction products that could produce a black oxidation product on a photographic layer processed with such a composition, the contact of sodium hydroxide with aluminum would produce, as one of the products of the reaction, hydrogen. It can be readily appreciated that, while one situation would produce a photographically deleterious result, the other would result in the premature rupture of the container and attendant loss of the processing composition.

The present invention, however, comprehends an inexpensive, preferably disposable, inert container particularly adapted to provide for retention of a liquid such as a photographic processing composition, which is in a quantity sufficient to carry out a single application to the respective surface of the sheet, or sheets, to be treated, wherein the retained liquid is effectively insulated from contact with externally derived vapor whereby to enhance the storage stability of such liquid, and wherein the fluid contents of the container are maintained in condition for direct application to said surfaces in an efficient and economical manner, especially when such container is directly affixed to, or in opposition to, a surface to be treated and further, wherein the failure of the container due to defects in the inner layer are substantially obviated.

The present invention is particularly concerned with a fluid container which will maintain the contents thereof, including organic nitrogen-containing compounds and/or caustic alkali liquids, substantially unaffected by external agents, including the container itself, for an extended time interval.

SUMMARY OF THE INVENTION The novel container of the present invention is prepared from a plurality of layers which include a layer of a metallic foil, a layer containing an acid reacting reagent and a polymeric layer inert to the photographic processing composition contained therein. Thus, any defects, such as pinholes or the like, in the polymeric layer, which permit the passage of minute quantities of the processing composition to pass therethrough and contact the metallic foil will not result in container failure as in the past, since the caustic material which penetrates the polymeric layer will be neutralized by the acid reacting reagent and then will not contact the metallic foil layer. The only reactants that may be formed will be the result of an acidbase reaction and not structurally or photographically deleterious. In a preferred embodiment, the thus-formed reaction products will be trapped in the layer containing the acidreacting reagent. Thus, containers which would in the past be discarded as failures because of the aforementioned defects in the inner layer can now be maintained structurally and photographically intact.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a perspective view of one form of fluid container prior to introduction of a liquid thereinto and subsequent clo sure of the container walls;

FIG. 2 is a cross-sectional view comprising the fluid container of FIG. 1 after introduction of a fluid photographic processing composition and closure of said containers walls;

FIG. 3 is a fragmentary plan view of the continuous material which is used in the formation of the container blanks of FIG. 1; and

FIG. 4 is a cross-sectional view of the continuous material of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION The novel container of the present invention employs an acid-reacting reagent in a layer located between the metallic foil layer and the processing composition to insulate the metallic foil layer from processing composition penetrating inner layers. The term acid-reacting reagent" is intended to refer to any compound which will react with the alkali in the processing composition to trap or precipitate or neutralize the alkali to prevent the alkali from contacting the metal foil and preferably refers to compounds which possess acid groups, preferably nondiffusing acid groups, i.e., the acid groups are anchored or ballasted by, for example, attachment to a polymer, so that the alkali will be trapped in the acid-reacting layer and thus not be able to contact the metallic foil layer nor can the reactive products diffuse back into the processing composition.

In one embodiment, the container will be an elongated structure, having a length of at least twice its width, and is relatively flat, having a depth which is only a fraction of its width. The container also will be deformable in its filled and sealed condition so that it can be curved in the direction of its width, for example, about a radius equal to its width, without danger of rupturing its seal. A sealed passage will extend the length of the container along one edge thereof and will be the weakest of the edge seals which define the liquid containing cavity and which confine the contents of said cavity.

The present invention is specifically concerned with improved fluid containers, of the last-mentioned type, which include, in general, a relatively thin, flexible layer of metallic foil having a continuous layer containing acid-reacting reagent superposed on one surface and adjacent said continuous layer, a continuous polymeric layer; preferably a laminate structure which includes an outer layer comprising a continuous polymeric layer, a layer of metallic foil, a layer containing acid-reacting reagent, and a polymeric inner lining, or layer, inert with respect to the photographic processing composition to be retained therein, for example, inert to the conventional, highly caustic, organic nitrogen-containing photographic processing compositions commercially employed in the photographic industry. A particularly preferred structure also includes, in addition to the aforementioned layers, a layer of epoxy resin, such as the EPON Resins (trade designation of Shell Chemical Corporation, New York, New York, for a commercially distributed condensation product of bisphenol A and epichlorohydrin).

In addition, the present invention is concerned with providing frangible containers, of the last-mentioned type, possessing at least one flexible and deformable wall, which exhibits differential strength of the containers respective edge seals, thus facilitating substantially uniform rupture and distribution of the containers retained fluid contents, by means of a predetermined passage orifice, upon the application of stress to the containers deformable surfaces.

The container is most preferably formed from a single, essentially rectangular blank folded medially, as illustrated in FIG. 1. The container is constructed of a multilayer material comprising walls 1 and 2, said individual walls being formed by media] fold 3. A surface portion of one of said walls as, for example, portion 4 of wall 2, is suitable for receiving and in part confining said liquid, and a substantially equal surface portion of the other of said walls as, for example, surface portion 5 of wall 1 is suitable for further confining said fluid upon closure of said walls. The container may also be formed from two essentially rectangular blanks secured together at marginal edges. It is so simply constructed that the container blank of FIG. 3, from which the container is formed, may be cut without waste from a continuous strip of laminated sheet material, permitting the material of the container walls to be processed and the container to be filled, sealed and served as part of one continuous operation.

The aforesaid fluid container is preferably constructed, as illus,rated in FIG. 2, of an outer layer 6 as a backing layer, said outer layer 6 being preferably formed of a thin, deformable, tough polymeric material, generally in the order of 0.00025 to 1 mil in thickness as, for example, a polyester such as polyethylene terephthalate and the like or paper 0.00035 to 4 mils, preferably 1 mil. A thin fllm, or sheet 7 comprising aluminum or lead foil approximately 0.00025 to 1.5 mil in thickness, preferably 0.7 mil, and having its dimensions predetermined according to the intended use, has layer 6 suitably adhered thereto and/or coated thereon as, for example, by means of a conventional adhesive composition such as DuPont Adhesive No. 46950 (trade designation of E. l. Du- Pont de Nemours and Co., Wilmington, Delaware, for a commercially distributed polyester resin adhesive) or Morton 503 (trade designation of Morton Chemical Company, Chicago, Ill, for a commercially distributed cross-linked polyester resin adhesive) where layer 6 comprises a polyester. Layer 20 has an acidreacting reagent disposed therein, e.g., a continuous material having acid groups attached thereto, generally 0.1 to 1.5 mils, preferably 0.2 to 0.9 mils in thickness. A layer 8 comprising a thermoplastic material, inert to the fluid composition to be retained within the container, for example, fluid photographic processing composition 9, such as polymerized vinyl chloride, for example, 90 percent vinyl chloride and 10 percent vinyl acetate, the aforementioned polyester, approximating 0.5 mil in thickness, preferably overcoated with, or having adhered by means of the last-identified adhesive, polymerized vinyl chloride, polymerized vinyl butyral, and the like, approximating l to 2 mils in thickness, is suitably adhered to and/or coated on one surface of layer 20. In a particularly preferred embodiment, an additional layer of an epoxy resin is interposed between layers 7 and 20.

Where desired, however, the illustrated container may comprise metal foil layer 7, a layer of acid-reacting reagent and inner liner, or layer 8, as the sole essential layers forming the container walls, whereupon metal foil layer 7 is, in effect, the outer layer of the walls.

The respective polymeric layers, coating or liners may be adhered to the metal foil layer by any of the coating and/or laminating procedures well known to the art. Where the polymeric layer, or layers, are precast and then laminated to the foil layer, it will be preferred to utilize an adhesive coating or layer, which adhesive layer is itself stable, or stabilized, against interaction with the containers fluid contents, and is selected based upon its adhesive capacity with respect to effecting a uniform bond between the selected polymeric film and the metal foil. The employment of an intermediate adhesive layer also affords an additional layer enhancing the stability of the container, and its retained liquid, by providing an added barrier coating for retaining the containers liquid contents. Alternatively, the polymeric layer may be directly coated on the foil layer, for example, by hot melt extrusion of thermoplastic polymer, for example, a thermoplastic vinyl polymer, such as polymerized vinyl chloride or a thermoplastic olefinic polymer such as polymerized ethylene or porpylene, or the like, on the respective surface, or surfaces, of the foil layer.

In the completed, closed liquid-carrying container, polymeric layer 8 serves both to substantially prevent direct contact of the retained fluid with vapor impervious foil layer 7 or acid-reacting reagent layer 20 and as a means of bonding together the facing marginal portions of said container bordering the enclosed liquid when, for example, the marginal por tions are subjected to direct sealing by means of heat and/or pressure and/or an adhesive composition and thus, upon bonding of said portions, provides means for sealing the liquid within the container.

The adhesive composition, illustrated by numeral 10, may be overlaid on a marginal portion 11 of polymeric layer 8 which, when bonded to a facing marginal polymeric portion 12, may serve as a means for bonding the facing marginal portions differentially with respect to other facing marginal portions 13, 14,15 and 16.

Upon closure of walls 1 and 2, marginal surface portions 11, 13 and 15 come into contact with marginal surface portions 12, 14 and 16, respectively, and may be suitably bonded together, as previously noted, and when thus bonded, provide, in conjunction with fold 3, means for effecting a completely sealed enclosure, or space.

Referring to FIG. 3, there is shown a blank 17 from which a preferred embodiment of the present inventions novel container may be formed, said blank 17, as shown, being substantially rectangular in shape and having a length equal to the container length and width approximately twice the width of the finished, filled container. As previously stated, blank 17 is preferably formed of a composite, deformable sheet material described above and comprising the plurality of strata illustrated in FIG. 4.

Outer polymeric layer 6, present in the preferred embodiment illustrated, as the aforementioned backing or support layer, has contiguous thereto layer 7 which, as detailed, is a thin film, or sheet, of vapor-impervious metal foil. Contiguous the opposite surface of said foil layer 7, is layer 20 containing acid-reacting reagents and layer 8 of thermoplastic material inert to, for example, fluid photographic processing composition. Layers 6 and 8 are relatively thin, generally being in the order of 0.5 mil in thickness, and as a practical matter, in the preferred embodiment need only be sufficiently thick to be characterized as continuous.

Along one edge of blank 17, there may be provided a strip 10 of a suitable thermoplasticcomposition which exhibits, preferably, a lesser adhesive affinity for polymeric layer 8 than the latter has for itself, for example, upon direct sealing and/or by means of the adhesive employed to affix marginal surface portions 13 to 14 and 15 to 16.

Container 19, illustrated in FIG. 2, is formed by folding blank 17 along a substantially medial line 3 extending the length of the container and then securing together the faces of marginal portions 13 to 14 and 15 to 16 along the edges of the container and the facing marginal surface portions 11 to 12 along the long edge of the container. As previously mentioned, the several marginal portions may be secured together by the application of heat and/or pressure and, in addition, it

may be preferable to adhesively secure together a narrow strip 18 of the container walls adjacent to the fold line 3. This latter provides a thin leading edge for the container over which a suitable pressure-applying device, such as a pressure roll, or doctor blade, may readily advance to compress the container walls and to thereby effect the release of the container contents by differential hydraulic rupture of the sealed marginal surfaces, preferably along the long edge of the container. As illustrated, the seal along the long edge of the container is preferably effected between inner polymeric layer 8 and the material of strip 10 which, as hereinbefore indicated, may be a material which possesses a lesser adhesive affinity for polymeric layer 8 than the polymeric layer does for itself as adhered in the remaining marginal portions. Thus the latter bonds exhibit an adhesive capacity substantially stronger than the seal along the long edge.

This structure assures a unidirectional release of the containers contents upon application of compressive force to the walls of the container. In one preferred embodiment, to insure a uniform separation of the marginal portions along the long edge of the container, when the container is subjected to a liquid releasing force, strip 10 not only extends to the very edge of the container but is also substantially wider than the width of the seal between marginal portions 11 and 12 and additionally extends within the liquid confining cavity of the container, as shown in FIG. 2. A further precaution against the hazard of an uneven seal consists in displacing the blank containing strip 10 beyond the long edge of the blank to which it is adhered. As a result, strip 10 projects beyond both long edges of the bond.

Where inner polymeric layer 8 comprises the previously identified preferred polymer, polyvinyl chloride, coating 10 may comprise any one of the following illustrative compositrons:

1. 50 cc. of a 10 percent solution of Saran F-120 (trade name of Dow Chemical Company, Midland, Michigan, for a thermoplastic resin produced by the polymerization of vinylidene chloride) in methylethyl ketone and 10 cc. of a 10 percent solution of nitrocellulose in methylethyl ketone;

2v 100 cc. of a composition comprising: 100 g. of Acryloid B-75 (solid) [trade name of Rohm & Haas Company, Philadelphia, Pennsylvania, for an acrylic ester resin], 3.4 g. of second cellulose nitrate, and 86.5 cc. of ethyl acetate;

3. 80 cc. of a 10 percent solution of ethyl cellulose in methylethyl ketone and cc. of a 10 percent solution of Acryloid 8-72; and 100 cc. ofa composition comprising: 5 g. of Bakelite NYGL (trade names of Bakelite Corporation, a division of Union Carbide and Carbon Corporation, New York, New York, for polyacrylonitrilepolyvinyl chloride resins), 100 cc. of acetone, 1 g. of Saran F-120 and 3 g. of Acryloid 13-72 (solid).

Where inner liner 8 comprises a polyvinyl acetal such as polyvinyl formal, polyvinyl acetal, polyvinyl butyral, and the like, preferably polyvinyl butyral, thermoplastic adhesive coating 10 may comprise, for example, ethyl cellulose, a mixture comprising ethyl cellulose and paraffin at a ratio of 1:1, and the like.

The acid-reacting reagent is preferably dispersed in an alkali permeable polymeric matrix, and more preferably is anchored or ballasted to be nondiffusible.

In one embodiment an acid such as a lower molecular weight acid such as citric or palmitic is employed in a matrix of, e.g., hydroxyethyl cellulose or coated directly on the adjacent layer. In an alternative embodiment a salt which forms an insoluble material with the alkali is employed, e.g., a metallic salt such as cadmium acetate, lead acetate, zinc nitrate, manganous acetate and the like. In still another alternative an acid ester is employed, such as diethyl tartrate.

In a particularly preferred embodiment the layer containing the acidreacting reagent is composed of a polymeric acid layer such as, for example, of the type set forth in US. Pat. No. 3,362,819.

As set forth in the last-mentioned patent, the polymeric acid layer comprises polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium, etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, preferably, nondiffusible from the acid polymer layer. In the preferred embodiments disclosed, the acid polymer contains free carboxyl groups and the processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming water-soluble sodium and/or potassium salts. One may also employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to inhibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids, mention may be made of dibasic acid half-ester derivatives of cellulose which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo-substituted aldehydes, e.g., o-, m-, or p-benzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methylvinyl ether/maleic anhydride copolymers; etc.

The quantity of acid-reacting reagent present may be selected at the option of the operator depending on the degree of protection desired. It is only necessary that the acid-reacting reagent be present in sufficient quantity to prevent any substantial contact with the metal foil by the ingredients of the processing composition which may penetrate the inner layer of the container.

In the formation of the container, the contents may be introduced as the containers walls are being sealed together. For example, the long edges of the container may be sealed together before the blank is severed from the stock of material from which it is formed. During the sealing together of the long edges, the desired quantity of liquid content from the container is introduced between the secured walls of the blank and thereafter the short edges are sealed together and the finished container severed from the remainder of the sheet stock. Under these conditions, the sealing is preferably effected by the application of heat and/or pressure, and uniform heat and/or pressure may be employed to all marginal portions being sealed together in view of the differential between the adhesive properties of strip 10 and those of polymeric layer 8. In the alternative, differential heat and/or pressure and/or marginal dimensions may be employed to effect differential adhesion between marginal portions 11 and 12 and the remaining marginal portions of the container, for providing a portion of the container prone to controlled fracture, or separation, to obtain directional release of the retained fluid composition.

In one preferred form of the container for spreading a liquid photographic processing composition to a thickness of approximately 0.003 of an inch of an area approximately 3 inches by 4 inches, a container 3% inches long and having maximum thickness of one-sixteenth of an inch can be used. The overall width of such container will be approximately three-quarters of an inch and the width of the seals at the marginal areas will be approximately three-sixteenths of an inch, while the seal at the release edge of the container will be approximately one-sixteenth of an inch.

The aforesaid material and constructions provide a container capable of substantially confining a liquid photographic processing composition adapted for processing an exposed photosensitive film, said containers effectively preventing loss of liquid content due to exudation, absorption, evaporation, and the like, and acting to preserve said fluid substantially free from environmental contamination. it will be understood that the liquid may be introduced into the container in an inert atmosphere.

It will be further understood that both the form and capacity of the container and the dimensions thereof are predetermined relative to the intended use of the subject container. It will be apparent that alternative forms and arrangements thereof may be provided within the scope of the invention. Such modifications may, for example, comprise a liquid-carry ing portion of the container having either a greater or lesser transverse or longitudinal dimension than the container shown, or the modified container may have separable mar ginal surface portions for releasing the retained fluid which vary from the straight-line portions illustrated above, or the container may be fabricated in accordance with the parameters set forth in U.S. Pat. No. 3,037,670.

Since certain changes may be made in the above product without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. ln a rupturable single use container having a pair of opposed walls secured together to provide a liquid-retaining cavity, at least one set of said walls being flexible and deformable, each of said walls comprising a plurality of layers at least one of said layers being metallic foil, the inner layer of each of said walls comprising a polymeric material inert to the liquid to be retained within said cavity and the bonded marginal portions of one edge of said pair of opposed walls exhibiting less adhesive capacity than the remaining marginal portions of said pair of opposed walls, the improvement which comprises a layer intermediate said metallic foil and said inner layer, said intermediate layer containing an acid-reacting reagent.

2. A product as defined in claim 1 wherein said metallic foil is lead.

3. A product as defined in claim 1 wherein said metallic foil is aluminum.

4. A product as defined in claim 1 wherein said layer containing an acid-reacting reagent comprises citric acid dispersed in hydroxyethyl cellulose.

5. A product as defined in claim 1 wherein said acid reacting reagent is polyacrylic acid.

6. A product as defined in claim 1 wherein said acid reacting reagent is the partial butyi ester of ethylene/maleic anhydride copolymer.

7. A product as defined in claim 1 wherein said polymeric material comprises polyvinyl chloride.

8. A product as defined in claim 1 wherein said polymeric material comprises polyvinyl butyral.

9. A product as defined in claim 1 wherein an outer layer comprising a polymeric material is positioned on the surface of said metallic foil opposite the side adjacent to the layer containing said acid reacting reagents.

10. A product as defined in claim 9 wherein said polymeric material comprising said outer layer comprises polyethylene terephthalate.

11. A product as defined in claim 1 wherein a thermoplastic adhesive is positioned between the bonded marginal portions of said edge exhibiting substantially less adhesive capacity than said remaining marginal portions, said thermoplastic adhesive exhibiting substantially less adhesive affinity for said polymeric material than said polymeric material exhibits for itself, said remaining marginal ortions being adhered together by said polymeric material onded to itse f, whereby said container preferentially opens along said bonded marginal portions of said edge exhibiting substantially less adhesive capacity, upon application of pressure to said container.

12. A product as defined in claim 1 wherein said liquid-containing cavity retains a photographic processing composition.

13. A product having a pair of opposed walls secured together to provide a liquid retaining cavity, at least one of said walls being flexible and deformable, each of said walls comprising a plurality of essential layers, said plurality of layers including successively an outer layer comprising paper, a layer comprising aluminum foil, a layer comprising an epoxy resin, a layer containing the partial butyl ester of ethylene/maleic anhydn'de copolymer, and an inner layer comprising polyvinyl chloride, and the bonded marginal portions of one edge of said pair of opposed walls exhibiting substantially less adhesive capacity than the remaining marginal portions of said pair of opposed walls. 

2. A product as defined in claim 1 wherein said metallic foil is lead.
 3. A product as defined in claim 1 wherein said metallic foil is aluminum.
 4. A product as defined in claim 1 wherein said layer containing an acid-reacting reagent comprises citric acid dispersed in hydroxyethyl cellulose.
 5. A product as defined in claim 1 wherein said acid reacting reagent is polyacrylic acid.
 6. A product as defined in claim 1 wherein said acid reacting reagent is the partial butyl ester of ethylene/maleic anhydride copolymer.
 7. A product as defined in claim 1 wherein said polymeric material comprises polyvinyl chloride.
 8. A product as defined in claim 1 wherein said polymeric material comprises polyvinyl butyral.
 9. A product as defined in claim 1 wherein an outer layer comprising a polymeric material is positioned on the surface of said metallic foil opposite the side adjacent to the layer containing said acid reacting reagents.
 10. A product as defined in claim 9 wherein said polymeric material comprising said outer layer comprises polyethylene terephthalate.
 11. A product as defined in claim 1 wherein a thermoplastic adhesive is positioned between the bonded marginal portions of said edge exhibiting substantially less adhesive capacity than said remaining marginal portions, said thermoplastic adhesive exhibiting substantially less adhesive affinity for said polymeric material than said polymeric material exhibits for itself, said remaining marginal portions being adhered together by said polymeric material bonded to itself, whereby said container preferentially opens along said bonded marginal portions of said edge exhibiting substantially less adhesive capacity, upon application of pressure to said container.
 12. A product as defined in claim 1 wherein said liquid-containing cavity retains a photographic processing composition.
 13. A product having a pair of opposed walls secured together to provide a liquid retaining cavity, at least one of said walls being flexible and deformable, each of said walls comprising a plurality of essential layers, said plurality of layers including successively an outer layer comprising paper, a layer comprising aluminum foil, a layer comprising an epoxy resin, a layer containing the partial butyl ester of ethylene/maleic anhydride copolymer, and an inner layer comprising polyvinyl chloride, and the bonded marginal portions of one edge of said pair of opposed walls exhibiting substantially less adhesive capacity than the remaining marginal portions of said pair of opposed walls. 